Enhancing lithography operation for manufacturing semiconductor devices

ABSTRACT

A method of treating a surface of a reticle includes retrieving a reticle from a reticle library and transferring the reticle to a treatment device. The surface of the reticle is treated in the treatment device by irradiating the surface of the reticle with UV radiation while ozone fluid is over the surface of the reticle for a predetermined irradiation time. After the treatment, the reticle is transferred to an exposure device for lithography operation to generate a photo resist pattern on a wafer. A surface of the wafer is imaged to generate an image of the photo resist pattern on the wafer. The generated image of the photo resist pattern is analyzed to determine critical dimension uniformity (CDU) of the photo resist pattern. The predetermined irradiation time is increased if the CDU does not satisfy a threshold CDU.

BACKGROUND

During an integrated circuit (IC) design, a number of patterns of theIC, for different steps of IC processing, are generated on a substrate.The patterns may be produced by projecting, e.g., imaging, by extremeultraviolet (EUV) radiation, layout patterns of a mask on a photo resistlayer of the wafer. A lithographic process transfers the layout patternsof the reticles to the photo resist layer of the wafer such thatetching, implantation, or other steps are applied only to predefinedregions of the wafer. The reticles, e.g., the masks, may be stored inreticle libraries under a vacuum condition when the reticles are notused. It is desirable to treat the reticles to increase the reflectivityof the reticles after being retrieved from the reticle library andbefore being used for the lithographic process.

BRIEF DESCRIPTION OF THE DRAWING

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 shows a process flow for generating a photo resist pattern on asemiconductor substrate.

FIG. 2 shows a wafer exchange system for retrieving the reticles andtreating the reticle in accordance with some embodiments of the presentdisclosure.

FIG. 3 shows a process flow for generating a photo resist pattern on asemiconductor substrate in accordance with some embodiments of thepresent disclosure.

FIG. 4 shows a schematic view of an exposure device for generating aphoto resist pattern on a wafer.

FIGS. 5A and 5B show cross-sectional views of a reflective reticlestructure and projecting the reflective reticle structure on asemiconductor device in an exposure device.

FIG. 6 shows an inspection system of the photo resist pattern disposedon a semiconductor substrate.

FIGS. 7A, 7B, 7C, 7D, and 7E show treatment devices for treatment of areticle, detecting the reflected light from a reflective reticle duringtreatment, and displaying the composition of the top layers of thereticle before and after the treatment in accordance with someembodiments of the present disclosure.

FIG. 8 shows a control system for treatment of a reticle and projectinglayout patterns of the treated reticle on a semiconductor substrate inaccordance with some embodiments of the present disclosure.

FIG. 9 shows a process of an exemplary process for treatment of areticle and projecting layout patterns of the treated reticle on asemiconductor substrate in accordance with some embodiments of thepresent disclosure.

FIGS. 10A and 10B illustrate an apparatus for treatment of a reticle andprojecting layout patterns of the treated reticle on a semiconductorsubstrate in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. In addition, the term“being made of” may mean either “comprising” or “consisting of.” In thepresent disclosure, a phrase “one of A, B and C” means “A, B and/or C”(A, B, C, A and B, A and C, B and C, or A, B and C), and does not meanone element from A, one element from B and one element from C, unlessotherwise described.

In some embodiments, the reticles are stored in the reticle library andthe reticle library is maintained under vacuum condition to prevent thedeposition of particles and hydrocarbon contamination on the reticles.However, when the reticle is used during a lithographic process,particles and hydrocarbon contamination may build up on the reticles. Inaddition, an oxide layer, e.g., an oxide of the absorption layer, maydeposit on the top surface of reticle or the composition of the toplayers of the reticle may modify. In addition to the particles and thehydrocarbon contamination, the deposited oxide layer and the change inthe composition of the top layers of the reticle, may reduce thereflectivity of a reflective reticle and may affect, e.g., reduce, thecritical dimension (CD) uniformity in the pattern produced on the photoresist layer of the wafer. In some embodiments, the reticle surfaces arecleaned from particles and hydrocarbon contamination with solvents afterthe reticle is retrieved from the reticle library. In some embodiments,the reticle surfaces are cleaned from particles and hydrocarboncontamination with solvents before the reticle is stored in the reticlelibrary. Cleaning the reticles with solvents, may introduce otherparticles in the reticle library if the reticles is cleaned before beingstored. Cleaning the reticles with solvents, may introduce otherparticles in the exposure device of the lithographic system if thereticle is cleaned after being retrieved from the reticle library. Inaddition, cleaning the reticle with solvents may introduce a long delayin the lithographic process. Thus, in some embodiments, the reticles arecleaned offline. The reticles are retrieved from the reticle library,the retrieved reticles are cleaned, and the reticles are stored again inthe reticle library. Cleaning the reticles with solvents may not reducethe deposited oxide layer on top surface of the reticle and may notremedy the modified composition of the top layers of the reticle.

As discussed, when the reticles are retrieved from the reticle libraryand are used for the lithographic process, particles and/or hydrocarboncontamination can build up on the mask, an oxide layer may deposit onthe top surface of reticle, and the composition of the top layers of thereticle may modify. Therefore, it is desirable to clean the reticles toremove the particles and/or hydrocarbon contamination before performingthe lithographic process. In addition, it is desirable to treat the toplayers of the reticle to remedy the deposited oxide and the modifiedcomposition of the top layers of the reticle. In some embodiments, thelithographic system includes a treatment device in addition to theexposure device. The exposure device is used for projecting the reticleson a photo resist layer of a wafer to pattern the wafer. The treatmentdevice with an ozone fluid supply and a separate radiation source, e.g.,a UV radiation source, is used for irradiating a surface layer of thereticle and treating the surface layer of the reticle when ozone fluid,e.g., ozone water or ozone gas is released on the top surface of thereticle. In some embodiments, the energy of the irradiation is used todecompose the particles or a hydrocarbon contamination layer depositedon the surface layer of the reticle. In addition, the energy of theirradiation and the ozone fluid on top surface of the reticle may beused to remedy the deposited oxide and the modified composition of thetop layers of the reticle. In addition, the more the surface layer ofthe reticle is irradiated, the more the particles and the hydrocarboncontamination layer are decomposed and the deposited oxide and themodified composition of the top layers of the reticle are affected. Insome embodiments, the reticle is a reflective reticle and irradiatingthe surface layer of the reticle for a long time not only cause delay inthe lithographic process, the extra irradiation may damage the layers ofthe reticle. Damaging the layers of the reticle, e.g., the reflectivelayers of the reflective reticle may damage CD uniformity. Therefore, itis desirable to irradiate the surface layer of the reticle to reduce oreliminate the effect of the particles and the hydrocarbon contaminationand to remedy the deposited oxide and the modified composition of thetop layers of the reticle but do not damage the structure, e.g., thereflective structure, of the reticle. Thus, it is desirable to irradiatethe surface layer of the reticle to get an optimum improvement in CDuniformity (CDU) before damaging the reticle structure.

FIG. 1 shows a process flow 150 for generating a photo resist pattern ona semiconductor substrate. In some embodiments, the process flow 150 isperformed by the control system 800 of FIG. 8 and/or the computer system1000 of FIGS. 10A and 10B. In a resist coat operation 102, a resistlayer of a resist material is disposed, e.g., coated, on a top surfaceof a substrate, e.g., a wafer or a work piece. As shown in FIG. 5B, aphoto resist layer 15 is disposed over a semiconductor substrate 10. Thepost application bake (PAB) is performed at a PAB operation 104 and thesemiconductor substrate 10 including the photo resist layer 15 is bakedto drive out solvent in the resist material and solidify the photoresist layer 15 on top of the semiconductor substrate 10.

In the present disclosure, the terms mask, photomask, and reticle areused interchangeably. In addition, the terms resist and photo resist areused interchangeably. At a mask retrieve operation 105, a reticle isretrieved from a reticle library. The mask retrieve operation 105 isdescribed in more details with respect to FIG. 2 . The retrieved reticleis loaded by a mask load and exposure operation 108 to an exposuredevice, which is described with respect to FIG. 4 . The mask load andexposure operation 108 also projects the mask, using actinic radiationof a radiation source onto the photo resist layer 15 of thesemiconductor substrate 10. In some embodiments, a layout pattern on themask is projected by an extreme ultraviolet (EUV) radiation from an EUVlight source, having a wavelength of 13.5 nm, onto the photo resistlayer 15 to generate a resist pattern in the photo resist layer 15 onthe semiconductor substrate 10. A post exposure bake (PEB) is performedat a PEB operation 110 on the wafer where the resist layer is furtherbaked after being exposed to the actinic radiation and before beingdeveloped in a development operation 112. By applying a developersolution to the photo resist layer 15, the resist material of the resistlayer is developed. For a positive tone resist material, in thedevelopment operation 112, the exposed regions are developed by applyinga developer solution and then the developed regions are removed and theremaining regions generate the resist pattern of the photo resist layer15. For a negative tone resist material, in the development operation112, the non-exposed regions are developed by applying the developersolution and the developed regions are subsequently removed and theremaining regions generate the resist pattern of the photo resist layer15. The mask is described with respect to FIG. 5A.

FIG. 2 shows a wafer exchange system 200 for transferring reticlesbetween different positions. The wafer exchange system 200 transfersreticles between a reticle library 202, a treatment device 212 and anexposure device 214. The wafer exchange system 200 includes a robotdevice 206 with a robot arm. The robot arm includes a first movablesegment 204 and a second movable segment 208. The second movable segment208 rotates around the first pivot point 205. The first movable segment204 rotates around a second pivot point (not shown) inside the robotdevice 206 and further moves the first pivot point and the secondmovable segment. The robot device 206 may rotate the first movablesegment 204 and the second movable segment 208 around the respectivepivot points to extend the robot arm to the reticle library 202, thetreatment device 212, or the exposure device 214. In some embodiments,the robot device 206, the reticle library 202, the treatment device 212,and the exposure device 214 are maintained in vacuum condition.

The wafer exchange system 200 also includes a wafer exchange controller240 coupled to the reticle library 202, the robot device 206, thetreatment device 212, and the exposure device 214. In some embodiments,the wafer exchange controller 240 commands the robot device 206 toretrieve a reticle from the reticle library 202 and load the reticle tothe treatment device 212 or the exposure device 214. In someembodiments, the wafer exchange controller 240 commands the robot device206 to retrieve a reticle from the treatment device 212 and to load thereticle to the exposure device 214. In some embodiments, the waferexchange controller 240 commands the robot device 206 to retrieve areticle from the exposure device 214 and to load the reticle to thetreatment device 212.In some embodiments, the wafer exchange controller240 commands the reticle library 202 to release one of the reticles tobe retrieved. In some embodiments, the wafer exchange controller 240commands the robot device 206 to load the reticle on a reticle stage(not shown) of the treatment device 212 or the exposure device 214. Thetreatment devices 212 and the exposure device 214 are described withrespect to FIGS. 4, 5B, and 7A.

FIG. 3 shows a process flow 300 for generating a photo resist pattern ona semiconductor substrate in accordance with some embodiments of thepresent disclosure. The process flow 300 includes the resist coatoperation 102, the PAB operation 104, the PEB operation 110, and thedevelopment operation 112 of the process flow 150 of FIG. 1 . Inaddition, the process flow 300 includes a mask retrieve operation 105,which is performed by the wafer exchange system 200 of FIG. 2 . In themask retrieve operation 105, the wafer exchange controller 240 of FIG. 2commands the robot device 206 and the reticle library 202. In responseto the commands from the wafer exchange controller 240, the reticlelibrary 202 releases a reticle and the robot arm of the robot device 206extends into the reticle library 202 and retrieves the released reticle.The process flow 300 also includes a mask load and treat operation 106.In the mask load and treat operation 106, the wafer exchange controller240 commands the robot device 206 to load the released reticle in thetreatment device 212. In addition, after the loading of the reticle inthe treatment device 212, the wafer exchange controller 240 commands aradiation source, e.g., a light source of the treatment device 212 toirradiate the surface of the reticle with a radiation of the radiationsource for a predetermined amount of time to clean the surface of thereticle from particles and/or hydrocarbon contamination and to remedythe deposited oxide and the modified composition of the top layers ofthe reticle as shown in FIGS, 7B, 7C, and 7D. In some embodiments, theradiation source of the treatment device 212 is a UV light source oranother light source with suitable wavelength that may decompose thehydrocarbon contamination layer and the particles or may remedy thedeposited oxide and the modified composition of the top layers of thereticle. In some embodiments, the surface of the reticle is a surfacearea of the reflective reticle that the radiation enters the reticle. Insome embodiments, as at least part of the cleaning and treatmentoperations and to determine the irradiation time of the surface of thereticle, the reflected light from the reticle is focused onto a lightdetector and a signal proportional to the detected light is generated bythe light detector. Also, in the mask load and exposure operation 108,the reticle loaded in the treatment device 212 is transferred to theexposure device 214 and a radiation source of the exposure device 214,projects the layout pattern of the reticle onto a photo resist layer ofa substrate, e.g., the photo resist layer 15 of the semiconductorsubstrate 10 of FIG. 5B to generate a resist pattern.

FIG. 4 shows a schematic view of an exposure device 400 for generating aphoto resist pattern on a wafer. The exposure device 400, which isconsistent with the exposure device 214 shows the exposure of a photoresist coated substrate with a patterned beam of radiation 29 from aradiation source 100, e.g., an EUV radiation source. In someembodiments, the exposure device 400 is an integrated circuitlithography tool such as a stepper, scanner, step and scan system,direct write system, device using a contact and/or proximity mask, etc.,provided with one or more optics 205 a , 205 b of an optical system, forexample, to illuminate a patterning optic, such as a reticle, e.g., areflective mask 205 c , with a beam of EUV radiation, to produce apatterned beam, and one or more reduction projection optics 205 d , 205e , of the optical system for projecting the patterned beam onto thetarget semiconductor substrate 10. In some embodiments, the photo resistlayer consistent with the photo resist layer 15 of FIG. 5B is disposedover the semiconductor substrate 10. A mechanical assembly (not shown)may be provided for generating a controlled relative movement betweenthe target semiconductor substrate 10 and patterning optic, e.g., areflective mask 205 c . By the controlled relative movement, differentdice of the substrate are patterned. In some embodiments, the exposuredevice 400 is an EUV lithography (EUVL) exposure device. As furthershown, the EUVL exposure device of FIG. 4 further includes the EUVradiation source 100 to irradiate the target semiconductor substrate 10.In some embodiments, because gas molecules absorb EUV light, thelithography system for the EUV lithography patterning, e.g., theexposure device 400 is under a vacuum environment to avoid EUV intensityloss. In some embodiments, a pressure inside the exposure device 400 issensed by a pressure sensor 408 inside the exposure device 400 and iscontrolled by a vacuum pressure controller 406 that is coupled to theexposure device 400. In some embodiments, the reflective mask 205 c isconsistent with the reticle 80 described below with respect to FIG. 5A.In some embodiments, the reflective mask 205 c is mounted on a reticlestage 402. In some embodiments, the vacuum pressure controller 406 isincluded in the wafer exchange controller 240 of FIG. 2 .

FIGS. 5A and 5B show cross-sectional views of a reflective reticlestructure 80 and projecting the reflective reticle structure 80 on asemiconductor device 34 in an exposure device. FIG. 5A shows thecross-sectional view 500 of the reticle 80, e.g., a reflective reticleor mask. As noted above, the terms mask, photomask, and reticle may beused interchangeably. The reflective reticle structure 80 is consistentwith reflective mask 205 c of FIG. 4 and is used in the exposure device400 of FIG. 4 . As shown in FIG. 5A, the reticle 80 includes a substrate30 with a suitable material, such as a low thermal expansion material orfused quartz. In various examples, the material includes TiO2 dopedSiO₂, or other suitable materials with low thermal expansion. The maskincludes multiple reflective layers (ML) 35 deposited on the substrate30. The ML includes a plurality of film pairs, film 37 and film 39, suchas molybdenum-silicon (Mo/Si) film pairs (e.g., a layer of molybdenumabove or below a layer of silicon in each film pair). Alternatively, theML 35 may include molybdenum-beryllium (Mo/Be) film pairs, or othersuitable materials that are configurable to highly reflect the EUVlight. The mask may also include a capping layer 40, such as ruthenium(Ru), disposed on the ML for protection. The mask further includes anabsorption layer 45, such as a tantalum boron nitride (TaBN) layer,deposited over the ML. The absorption layer 45 is patterned to define alayout pattern 55 for a layer of an integrated circuit (IC).Alternatively, another reflective layer may be deposited over the ML andis patterned to define a layer of an integrated circuit, thereby formingan EUV phase shift mask.

FIG. 5B shows exposing the photo resist layer disposed over asemiconductor device to radiation. FIG. 5B is a simplified drawingconsistent with FIG. 4 for projecting a reflected mask on a substrate.FIG. 5B also shows the semiconductor device 34 that includes a photoresist layer 15 that is disposed on a semiconductor substrate 10 and isconsistent with the semiconductor substrate 10 of FIG. 4 . FIG. 5Bfurther shows a radiation beam 50 that is originated from an EUVradiation source, e.g., EUV radiation source 100 of FIG. 4 . Theradiation beam 50 is directed to the reticle 80, e.g., a reflectivephotomask, where the reflected beam 50′ is reflected from the reflectivephotomask 80 and is incident onto the photo resist layer 15 of thesemiconductor device 34. The incident angle of the reflected beam 50′,which is defined with respect to a line 302 that is perpendicular to atop surface of the semiconductor substrate 10 is an angle A. In someembodiments, the semiconductor substrate 10, that is consistent with thesemiconductor substrate 10 of FIG. 4 , is mounted on stage 560 that iscoupled to and controlled by a stage controller 565 for moving thesemiconductor device 34 and exposing different locations of thesemiconductor device 34. In some embodiments, as described, the exposureconfiguration 550 of FIG. 5B is part of the exposure device 400 of FIG.4 .

FIG. 6 shows an inspection system 600 of the photo resist patterndisposed on a semiconductor substrate 10. FIG. 6 shows the semiconductordevice 34 on a stage 660 and the stage 660 is coupled to and controlledby a stage controller 665. As described with respect to FIG. 2 , afterthe reticle is cleaned at the treatment device 212, the reticle isloaded as the reflective mask 205 c to the exposure device 400. In someembodiments, the semiconductor substrate 10 of FIG. 4 is thesemiconductor device 34 of FIG. 5B and the reflective mask 205 c isirradiated with the radiation beam of the radiation source 100 toproject the layout patterns of the reflective mask 205 c onto the photoresist layer 15 of the semiconductor device 34 to produce a resistpattern in the photo resist layer 15. In some embodiments, prior to theexposure, the semiconductor substrate 10 including the photo resistlayer 15 is baked in the PAB operation 104 to drive out solvent in theresist material and solidify the photo resist layer 15. In someembodiments, after the exposure, the PEB operation 110 is performed onthe photo resist layer 15. In some embodiments, after the PEB operation110, the development operation 112 is applied to the photo resist layer15 to produce the resist pattern in the photo resist layer 15.

FIG. 6 also shows a scanning-imaging device 635 that generates afocusing beam 619 for scanning a top surface of the photo resist layer15 and generating an image of the resist pattern at the top surface ofthe photo resist layer 15. In addition, FIG. 6 shows thescanning-imaging device 635 and a lens 634 that generates a uniform beam617 for imaging a top surface of the photo resist layer 15 andgenerating the image of the resist pattern on the top surface of thephoto resist layer 15. In addition, the scanning-imaging device 635 iscoupled to an analyzer module 630 that includes an image processing unit633 to receive and process the generated image of the top surface of thephoto resist layer 15. In some embodiments, the generated image of theresist pattern on the top surface of the photo resist layer 15 isinspected. In some embodiments, the image processing unit of theanalyzer module 630 performs one or more image processing and/or imagerecognition algorithms on the generated image of the top surface of thephoto resist layer 15 and determines a CD measurement of the resistpattern produced in the photo resist layer 15. In some embodiments, thefocusing beam 619 and the uniform beam 617 are light beams. In someembodiments, the focusing beam 619 is an electron beam. In someembodiments, as described before, the semiconductor device 34 is placedon the stage 660 and the stage controller 665 of the stage 660 moves thesemiconductor device 34 with respect to the scanning-imaging device 635.In some embodiments, the stage controller 665 coordinates thescanning-imaging device 635 and the movement of the semiconductor device34 that is placed on the stage 660 and enables the scanning-imagingdevice 635 to capture one or more images of the developed resist patternof the photo resist layer 15 disposed on the semiconductor device 34 atdifferent locations of the semiconductor device 34.

In some embodiments, the analyzer module 630 or the image processingunit 633 of the analyzer module 630 also determines a CD uniformity(CDU) of the developed resist pattern of the photo resist layer 15. Ifthe determined CDU satisfies a predetermined criterion, e.g., if the CDUis better than one percent, the analyzer module 630 determines that thepredetermined amount of time to clean the surface of the reticle fromparticles and/or hydrocarbon contamination and/or remedy the depositedoxide and the modified composition of the top layers of the reticle isenough, e.g., is acceptable. However, if the CDU does not satisfy thepredetermined criterion, the analyzer module 630 determines that thepredetermined amount of time to clean the surface of the reticle fromparticles and/or hydrocarbon contamination or to remedy the depositedoxide and the modified composition of the top layers of the reticle isnot enough, e.g., is not acceptable, and should be increased. In someembodiments, the analyzer module 630 gradually increases thepredetermined amount of time, e.g., the predetermined amount of time isincreased in steps of, for example, between about 2 percent to about 10percent. After each step of increasing the predetermined amount of time,the CDU is measured and if the CDU satisfies the predeterminedcriterion, the increase does not continue and the predetermined amountof time is decided as the amount of time that CDU satisfies thepredetermined criterion. In some embodiments, the predetermined amountof time depends on the details of the layout pattern of the mask andwhether specific shapes or features, e.g., holes, exist in the layoutpattern of the mask.

In some embodiments, the analyzer module 630 determines that thepredetermined amount of time to clean the surface of the reticle fromparticles and/or hydrocarbon contamination or remedy the deposited oxideand the modified composition of the top layers of the reticle isacceptable, however, the predetermined amount of time may be more thanthe time to satisfy the predetermined criterion. In some embodiments,the analyzer module 630 gradually decreases the predetermined amount oftime, e.g., the predetermined amount of time is decreased in steps of,for example, between about 2 percent to about 10 percent. After eachstep of decreasing the predetermined amount of time, the CDU is measuredand when at the step that the CDU does not satisfy the predeterminedcriterion, the decrease does not continue and the predetermined amountof time is decided as the amount of time before the immediate decreasethat caused the CDU to dissatisfy the predetermined criterion. In someembodiments, the decided predetermined amount of time is increased by apredetermined percentage, e.g., between about 0.5 percent to about 1.5percent, to increase reliability.

FIGS. 7A, 7B, 7C, 7D, and 7E show treatment devices for treatment of areticle, detecting the reflected light from a reflective reticle duringtreatment, and displaying the composition of the top layers of thereticle before and after the treatment in accordance with someembodiments of the present disclosure. The treatment device of FIG. 7Ashows irradiating the reticle 80 with a UV radiation beam 51, anincident light beam, from a UV light source—controller 705. In someembodiments, the UV light source—controller 705 generates the UVradiation beam 51, e.g., a UV light beam, at an incident angle B withrespect to a line 302 that is perpendicular to a surface 706 of thereticle 80. In some embodiments, the reticle 80 is a reflective reticleand a reflected UV radiation beam 51′ reflects back from the surface 706of the reticle 80. As shown in FIG. 7A, a fluid flow controller 775generates a fluid flow 715 from an ozone tank 772. The fluid flow 715 isdelivered via a pipe 702 and a nozzle 712 to the surface 706 of thereticle 80. In some embodiments, the ozone tank 772 contains ozone, thefluid flow 715 is an ozone fluid flow, and ozone molecules 708 aredelivered, e.g., released, over the surface 706 of the reticle 80. Insome embodiments, the ozone molecules 708 are distributed over thesurface 706 of the reticle 80 when the surface 706 of the reticle 80 isirradiated with the UV radiation beam 51. In some embodiments, thedistributed ozone molecules 708 over the surface 706 of the reticle 80,enhances the cleaning of the surface 706 of the reticle from particlesand/or hydrocarbon contamination and also improves the cure of thedeposited oxide and the modified composition of the top layers of thereticle 80. In some embodiments, the UV light source—controller 705 hasa wavelength between about 100 nm and about 400 nm. As describe, in someembodiments, the reticle 80 is a reflective EUV reticle and betweenabout 50 percent to 90 percent of the incident UV radiation beam 51 isreflected back from the surface 706 of the reticle 80 to generate thereflected UV radiation beam 51′ and the rest of the incident UVradiation beam 51 goes through the reticle 80. In some embodiments, theincident UV radiation beam 51 irradiates a first region of a pluralityof at least partially non-overlapping regions on the surface 706 of thereticle 80 and treats, e.g., remedies or cures, the first region of thesurface 706 of the reticle 80. In some embodiments, the reticle stage722 that is consistent with the reticle stage 402 of FIG. 4 moves andthe incident UV radiation beam 51 scans and treats an entire surface 706of the reticle 80. In some embodiments, the UV light source—controller705 changes the incident angle B of the incident UV radiation beam 51 toscan and treat the entire surface 706 of the reticle 80. In someembodiments, a remaining amount of the delivered ozone fluid flow 715 iscollected as a fluid flow 720 by a fluid collector 776. The fluid flow720 is collected via a nozzle 714 and a pipe 707 connected between thenozzle 714 and fluid collector 776. In some embodiments, as shown inFIG. 7A, the surface 706 of the reticle 80 is covered with ozone fluid.In some embodiments, the fluid flows 715 and 720 are ozone water, e.g.,ozone gas dissolved in water, and ozone water covers the surface of thereticle 80 when the incident UV radiation beam 51 irradiates the surface706 of the reticle 80. Thus, in some embodiments, the ozone tank 772 isan ozone water tank and the fluid flow controller 775 controls the flowof the ozone water from the ozone tank 772 to the surface 706 of thereticle 80 and the ozone molecules 708 on the surface 706 of the reticle80 are dissolved in water (not shown). In some other embodiments, theozone tank 772 is an ozone gas tank, the fluid flows 715 and 720 areozone gas and the ozone molecules 708 are provided as ozone gas to thesurface 706 of the reticle 80.

FIG. 7B shows a treatment device consistent with the treatment device ofFIG. 7A. FIG. 7B additionally includes a light detector system 710 thatincludes at least one light detector and focusing optics, e.g., a lens,and is coupled to the analyzer module 630. In some embodiments, thereflected UV radiation beam 51′ is focused on a single point by thelight detector system 710 and the light detector system 710 detects andgenerates a light signal 732 proportional to the detected light andsends the detected light signal 732 to the analyzer module 630. In someembodiments, the treatment of the ozone covered surface 706 of thereticle 80, remedies the deposited oxide and the modified composition ofthe top layers of the reticle 80 that are not covered by the absorptionlayer 45 and increases an intensity of the reflected UV radiation beam51′ and, thus, increases the detected light signal 732. The temporalvariation of the detected light signal 732 is described with respect toFIG. 7E.

FIG. 7C and 7D show treatment devices that are consistent with thetreatment device of FIG. 7B. FIGS. 7C and 7D additionally show acontamination layer 704 containing hydrocarbon contamination orparticles that is deposited over the surface 706 of the reticle 80 wherethe incident radiation beam 51 enters the reticle 80. In addition to thedeposited oxide and the modified composition of the top layers of thereticle 80, the contamination layer 704 may further reduce the intensityof the reflected beam 50′ in FIG. 5B and may further degrade theprojected image during lithography and may degrade CD uniformity. Insome embodiments, irradiating the ozone covered contamination layer 704with the UV radiation beam 51 decomposes the contamination layer 704. Asshown in the progression from FIG. 7C to FIG. 7D, the contaminationlayer 704 is decomposed and becomes thinner and the intensity of thereflected light from the surface 706 of the reticle 80 is increased. Inaddition to decomposing the contamination layer 704, the UV radiationbeam 51 may also cure the deposited oxide and the modified compositionof the top layers of the reticle 80 during and after the decompositionof the contamination layer 704 and, thus, may further increase thereflected light from the surface 706 of the reticle 80.

In some embodiments, irradiating the ozone covered reticle 80 with theUV radiation beam 51 and determining the CDU may be performed inmultiple steps where each step may last between about 10 seconds to 50seconds. After each step, the CDU is determined as described above. Ifthe CDU is determined to be below a threshold CDU, the treatment ofreticle 80 becomes complete. In some embodiments, the threshold CDU isabout one to two percent in 3 nm process for 3 nm semiconductor node.

FIG. 7E shows a time variation, on temporal coordinate 734, of thedetected reflected light signal 732, from a region on the surface 706 ofthe reticle 80. As shown in FIG. 7E, the reflected intensity from thespecific region increases in time until a time T1 that the intensitycurve saturates at level Si and does not increase further. The curve 738is an indication that at the specific region of the surface 706 of thereticle 80, the contamination layer 704 existed and/or the depositedoxide and the modified composition of the top layers of the reticle 80existed. The temporal change of the curve 738 also indicates that thecontamination layer 704 is decomposed and/or the deposited oxide and themodified composition of the top layers of the reticle 80 is cured. Asdiscussed, the procedure shown in FIGS. 7A, 7B, 7C, and 7D enhances,e.g., increases, the reflectivity of the surface 706 of the reticle 80,increases the reflected light from the surface 706 of the reticle 80and, thus, the required time for the lithography operation may bereduced. In some embodiments, the exposure time of the lithographyoperation is inversely proportional to the reflectivity of the reticle80.

In some embodiments, the time T1 is the predetermined amount of timethat is needed to clean and cure the surface 706 of the reticle 80 andfurther irradiating the reticle 80 does not improve the reflected lightintensity. In some embodiments, when the curve 738 saturates andincreases by less than a threshold value in a predefined time, e.g., thecurve 738 increase by less than one percent in a predefined time betweenabout 10 seconds and about 100 seconds, the cleaning stops and the timeT1 is reached. In some embodiments, the time T1 is between about 50seconds to about 100 seconds. In some embodiments, the time T1 isbetween about 2 minutes and about 10 minutes. In some embodiments, thecurve 738 is constructed for multiple regions on the surface 706 of thereticle 80, the time T1 is measured for the multiple regions, and afinal T1 is determined as the maximum of the measured T1 s. In someembodiments, a minimum time for each step of cleaning and/or treatmentis T0, e.g., 10 seconds and, thus, the curve 738 begins at the time T0.In some embodiments, as described above, the reflectivity of the surface706 of the reticle 80 is determined using a UV light source and thedetermined cleaning and/or treatment time is used for cleaning and/ortreatment of the reticle 80 with the UV light source, however, alithography system that uses an EUV light source uses the cleaned andtreated reticle 80.

In some embodiments, after about 20 lithography operations, thereflected light intensity from the surface 706 of the reticle 80 isreduced from about 20 mili-joules to about 17.4 mili-joules as measuredby the light detector system 710 of FIG. 7B, however, after thetreatment the reflected light intensity is increased to about 18.6mili-joules. Thus, in some embodiments, the treatment does notcompletely cure the deposited oxide and the modified composition of thetop layers of the reticle 80, however, the treatment completely removesthe contamination layer 704.

FIG. 8 shows a control system 800 for treatment of a reticle andprojecting layout patterns of the treated reticle on a semiconductorsubstrate in accordance with some embodiments of the present disclosure.The control system 800 includes an analyzer module 830 and a maincontroller 840 coupled to each other. In some embodiments, the controlsystem 800 includes the stage controller 665 of FIG. 6 , the lightdetector system 710 of FIG. 7B, the wafer exchange controller 240 ofFIG. 2 , the scanning-imaging device 635 of FIG. 6 , and the vacuumpressure controller 406 of FIG. 4 . In some embodiments, the maincontroller 840 is coupled to and controls the stage controller 665, thelight detector system 710, the wafer exchange controller 240, thescanning-imaging device 635, and the vacuum pressure controller 406. Insome embodiments, the main controller 840 is directly coupled to thescanning-imaging device 635 or is coupled to the scanning-imaging device635 via the analyzer module 830. In some embodiments, the treatment ofthe reticle 80 includes the cleaning of the surface 706 of the reticle80.

In some embodiments, the analyzer module 830 is consistent with orincludes the analyzer module 630 of FIG. 6 . In some embodiments, themain controller 840 commands the scanning-imaging device 635, via theanalyzer module 830, to capture an image of the resist pattern on asemiconductor substrate and determine, e.g., measure, the CDU of theresist pattern disposed on the semiconductor substrate. As describedabove, the analyzer module 830 determines, based on the measured CDU, ifthe surface of the reticle is cleaned and or treated. In someembodiments, the main controller 840 commands the stage controller 665to move the stage 660 to capture one or more images of the resistpattern disposed on the semiconductor substrate at different locations.In some embodiments, the main controller 840 commands the vacuumpressure controller 406 to maintain a vacuum environment inside thetreatment device 212 and the exposure device 214 and to maintain avacuum environment inside the reticle library 202. In some embodiments,the main controller 840 commands the wafer exchange controller 240 toclean and/or treat a surface of the reticle in a treatment device 212and to load the cleaned and treated reticle to the exposure device 214and project the layout pattern of the reticle 80 on a photo resist layerof the semiconductor substrate 10. In some embodiments, the maincontroller 840 commands the light detector system 710 to capture areflected light from the reticle during the cleaning and or treating ofthe reticle 80 and to transfer the detected reflected light to theanalyzer module 830 for analysis. As described before, the analyzermodule 830 includes or is coupled to the image processing unit 633 andthe image processing unit 633.

FIG. 9 shows a process 900 of an exemplary process for treatment of areticle and projecting layout patterns of the treated reticle on asemiconductor substrate in accordance with some embodiments of thepresent disclosure. The process 900 or a portion of the process 900 maybe performed by the system of FIG. 2 . In some embodiments, the process900 or a portion of the process 900 is performed and/or is controlled bythe computer system 1000 described below with respect to FIGS. 10A and10B. In some embodiments, the process 900 or a portion of the process900 is performed by the control system 800 of FIG. 8 described above.The method includes an operation 5910, where a reticle is retrieved froma reticle library and is transferred to a treatment device. As shown inFIG. 2 , a reticle is retrieve by the robot arm of the robot device 206from the reticle library 202. After the retrieval of the reticle, therobot arm delivers the reticle to the treatment device 212.

In operation 5920, a surface of the reticle is treated by releasingozone fluid over the surface of the reticle and irradiating the surfaceof the reticle by UV radiation of a UV source for a predetermined amountof time. As shown in FIG. 7A, 7B, and 7C, the surface 706 of the reticle80 is treated, in the treatment device 212, to remove the contaminationlayer 704 and or to cure the deposited oxide and the modifiedcomposition of the top layers of the reticle 80. As shown in FIGS. 7Band 7D, the surface of the reticle 80 is cleaned from the contaminationlayer 704 and/or is cured for deposited oxide and the modifiedcomposition of the top layers of the reticle 80. In some embodiments,the treatment includes focusing a reflected UV beam from the surface ofthe reticle onto a detector of the light detector system 710 to generatea detected signal and sending the detected signal, via the maincontroller 840, to the analyzer module 830 such that the analyzer module830 monitors the detected signal during the irradiation time. In someembodiments, the analyzer module 830 sends a signal to the maincontroller to stop the irradiation time and to stop the treatment of thesurface of the reticle when a percentage increase of the detected signalis below a threshold value in a specific amount of time.

In operation S930, a reflected UV beam from the surface of the reticleis focused onto a detector to generate a detected signal, the detectedsignal is monitored, and the treatment is stopped when a percentageincrease of the detected signal is below a threshold value in a specificamount of time. As shown in FIG. 7B, the reflected beam 51′ is focusedon a detector of the light detector system 710 and the light signal 732is generated. The detected light signal 732 is transferred to theanalyzer module 630 and is monitored by the analyzer module 630. Whenthe analyzer module 630 determines that the percentage increase of thedetected light signal 732 is below a threshold, e.g., below 1 percent,in a duration of time of about 20 seconds, the treatment ends and the UVradiation beam 51 is turned off, the ozone fluid flow 715 is turned off,and the remaining amount of the delivered ozone fluid flow 715 iscollected as the fluid flow 720 by the fluid collector 776.

In operation 5940, after the treatment, the reticle is transferred fromthe treatment device to an exposure device for lithography operation. Asshown in FIG. 2 , after treating the reticle, the reticle is transferredfrom the treatment device 212 to the exposure device 214. The reticle istransferred by the robot arm of the robot device 206. In the exposuredevice 214 the lithography operation is performed and the layoutpatterns of the reticle 80 is projected on a wafer.

In operation 5950, in the exposure device, a layout pattern of thereticle is projected onto a photo resist layer of a wafer. As shown inFIG. 4 or 5B, the layout pattern of the respective reflective mask 205 cor 80 is projected onto a photo resist layer of the respectivesemiconductor substrate 10.

FIGS. 10A and 10B illustrate an apparatus for treatment of a reticle andprojecting layout patterns of the treated reticle on a semiconductorsubstrate in accordance with some embodiments of the present disclosure.FIGS. 10A and 10B illustrate an apparatus for treating a reticle andprojecting layout patterns of the cleaned reticle on a semiconductorsubstrate in accordance with some embodiments of the present disclosure.In some embodiments, the computer system 1000 is used for performing thefunctions of the modules of FIG. 8 that include the main controller 840,the analyzer module 830 or 630, the stage controller 665, the waferexchange controller 240, the vacuum pressure controller 406, and theimage processing unit 633 of the analyzer module 630. In someembodiments, the computer system 1000 is used to execute the process 900of FIG. 9 .

FIG. 10A is a schematic view of a computer system that performs thefunctions of an apparatus for treating reticles and projecting layoutpatterns of the treated reticles. All of or a part of the processes,method and/or operations of the foregoing embodiments can be realizedusing computer hardware and computer programs executed thereon. In FIG.10A, a computer system 1000 is provided with a computer 1001 includingan optical disk read only memory (e.g., CD-ROM or DVD-ROM) drive 1005and a magnetic disk drive 1006, a keyboard 1002, a mouse 1003, and amonitor 1004.

FIG. 10B is a diagram showing an internal configuration of the computersystem 1000. In FIG.10B, the computer 1001 is provided with, in additionto the optical disk drive 1005 and the magnetic disk drive 1006, one ormore processors, such as a micro processing unit (MPU) 1011, a ROM 1012in which a program such as a boot up program is stored, a random accessmemory (RAM) 1013 that is connected to the MPU 1011 and in which acommand of an application program is temporarily stored and a temporarystorage area is provided, a hard disk 1014 in which an applicationprogram, a system program, and data are stored, and a bus 1015 thatconnects the MPU 1011, the ROM 1012, and the like. Note that thecomputer 1001 may include a network card (not shown) for providing aconnection to a LAN.

The program for causing the computer system 1000 to execute thefunctions for treating the reticles and projecting layout patterns ofthe treated reticles in the foregoing embodiments may be stored in anoptical disk 1021 or a magnetic disk 1022, which are inserted into theoptical disk drive 1005 or the magnetic disk drive 1006, and transmittedto the hard disk 1014. Alternatively, the program may be transmitted viaa network (not shown) to the computer 1001 and stored in the hard disk1014. At the time of execution, the program is loaded into the RAM 1013.The program may be loaded from the optical disk 1021 or the magneticdisk 1022, or directly from a network. The program does not necessarilyhave to include, for example, an operating system (OS) or a third partyprogram to cause the computer 1001 to execute the functions of thecontrol system for treating the reticles and projecting layout patternsof the treated reticles in the foregoing embodiments. The program mayonly include a command portion to call an appropriate function (module)in a controlled mode and obtain desired results.

According to some embodiments of the present disclosure, a method oftreating a surface of a reticle for semiconductor manufacturing includesretrieving a reticle from a reticle library, transferring the reticle toa treatment device, and releasing ozone fluid over a surface of thereticle. The method also includes that while the ozone fluid is over thesurface of the reticle the surface of the reticle is irradiated with anincident ultraviolet (UV) radiation for a predetermined irradiation timeto treat the surface of the reticle. The method includes that after thetreatment, the reticle is transferred to an exposure device forlithography operation to generate a photo resist pattern on a wafer. Themethod further includes imaging a surface of the wafer to generate animage of the photo resist pattern on the wafer, analyzing the generatedimage of the photo resist pattern to determine critical dimensionuniformity (CDU) of the photo resist pattern, and increasing thepredetermined irradiation time if the determined CDU does not satisfy athreshold CDU. In an embodiment, the ozone fluid is either an ozonewater or an ozone gas, the method further includes maintaining thetreatment device, the exposure device, and the reticle library undervacuum environment. In an embodiment, the reticle is retrieved from thereticle library and is transferred to the treatment device by a robotarm of a wafer exchange system, and the method further includestransferring the reticle from the treatment device to the exposuredevice by the robot arm. In an embodiment, the method further includesprojecting, by an incident EUV radiation, a layout pattern of thereticle onto a photo resist layer of the wafer, and developing the photoresist layer to generate the photo resist pattern on the wafer. In anembodiment, the incident UV radiation is generated from a UV source ofthe treatment device and the incident EUV radiation is generated from anEUV source of the exposure device. In an embodiment, the threshold CDUis between one to two percent in 3 nm process for 3 nm semiconductornode. In an embodiment, the method further includes repeating thetreatment, the projecting, the developing, the imaging, the analyzing,and the increasing a irradiation time, until the determined CDUsatisfies the threshold CDU, and adjusting the predetermined irradiationtime to the irradiation time that corresponds to the threshold CDU.

According to some embodiments of the present disclosure, a method oftreating a surface of a reticle for semiconductor manufacturing includesperforming a treatment of a surface of a reflective reticle in atreatment device. The treatment includes releasing ozone fluid over thesurface of the reticle. The treatment further includes focusing areflected UV beam from the surface of the reticle onto a detector togenerate a detected signal, monitoring the detected signal during theirradiation time, and stopping the treatment of the surface of thereticle and ending the irradiation time when a percentage increase ofthe detected signal in a specific amount of time is below a thresholdvalue. The method also includes transferring the reticle, after thetreatment, from the treatment device to an exposure device forlithography operation. The method further includes projecting a layoutpattern of the reticle in the exposure device, using an incident extremeUV (EUV) radiation of an EUV source, onto a photo resist layer of awafer. In an embodiment, the method further includes developing thephoto resist layer, after the projecting, to generate a photo resistpattern on the wafer. In an embodiment, the treatment further includesirradiating a first region of two or more at least partiallynon-overlapping regions on the surface of the reticle by the incident UVbeam to treat the first region on the surface of the reticle, focusing areflected UV beam from the first region of the surface of the reticleonto the detector to generate the detected signal, monitoring thedetected signal during the irradiation time, and stopping the treatmentof the first region when the percentage increase of the detected signalis below the threshold value in the specific amount of time. In anembodiment, the two or more at least partially non-overlapping regionscover an entire surface of the reticle, the treatment further includesperforming the irradiating, the focusing, the monitoring, and thestopping on other regions of the two or more at least partiallynon-overlapping regions on the surface of the reticle to treat theentire surface of the reticle. In an embodiment, the UV source of thetreatment device produces UV radiation with a wavelength between 100 nmand 300 nm and the method further includes stopping the treatment of thefirst region when the detected signal increases less than one percent in20 seconds. In an embodiment, the EUV source of the exposure deviceproduces EUV radiation at a wavelength of 13.5 nm. In an embodiment, themethod further includes maintaining the exposure device and thetreatment device under a vacuum environment.

According to some embodiments of the present disclosure, a semiconductormanufacturing system includes a main controller, an analyzer modulecoupled to the main controller, and a wafer exchange system having anextendable robot arm. The system includes a treatment device thatincludes a first reticle stage for mounting a reticle, an ultra violet(UV) light source, and a light detector system including a lightdetector. The system further includes an exposure device that includes asecond reticle stage for mounting the reticle, an extreme ultra violet(EUV) light source, a stage for holding a wafer, and an optical system.The main controller commands the UV light source to turn on, toirradiate UV radiation from the UV light source, and to treat a surfaceof the reticle in the first reticle stage of the treatment device byirradiating the surface of the reticle by the UV radiation of the UVsource. The main controller allows release of ozone fluid from an ozonesupply line over the surface of the reticle during the irradiation withthe UV radiation. The main controller commands the light detector systemof the treatment device to focus a reflected UV beam from the surface ofthe reticle onto the light detector of the light detector system togenerate a detected signal and to send the detected signal to theanalyzer module. The analyzer module monitors the detected signal duringan irradiation time and sends a command via the main controller to theUV light source to stop a treatment of the surface of the reticle when apercentage increase of the detected signal is below a threshold value ina specific amount of time. After the treatment, the main controllercommands the wafer exchange system to transfer the reticle, by theextendable robot arm, from the treatment device to the second reticlestage of the exposure device for lithography operation. Moreover, afterthe transferring, the main controller commands the EUV light source toturn on, to irradiate EUV radiation from the EUV light source, and toproject a layout pattern of the reticle, through the optical system,onto a photo resist layer of the wafer. In an embodiment, the systemfurther includes a development system to develop the photo resist layerof the wafer after the projection of the layout pattern of the reticleand to generate a photo resist pattern on the wafer. In an embodiment,the exposure device further includes an imaging device mounted over thestage for holding a wafer. In response to a command from the maincontroller, the imaging device captures an image of the developed photoresist pattern on the wafer and transfers the captured image to theanalyzer module. The analyzer module determines a critical dimensionuniformity (CDU) of the photo resist pattern on the wafer. In anembodiment, the system further includes a reticle library to hold aplurality of reticles, and a pressure controller coupled to the maincontroller. The pressure controller maintains a pressure of the exposuredevice, the treatment device, and the reticle library under a vacuumenvironment. In an embodiment, the system further includes a reticlelibrary. Prior to the irradiating the surface of the reticle by the UVradiation, the main controller sends a command to the wafer exchangesystem to retrieve the reticle from the reticle library and to transferthe reticle to the treatment device. In an embodiment, the EUV lightsources have a wavelength of 13.5 nm and the UV light source has awavelength between 120 nm and 250 nm. The analyzer module sends acommand via the main controller to the UV light source to turn off tostop the treatment of the surface of the reticle when the detectedsignal increases less than one percent in 20 seconds. In someembodiments, the UV light source emits a light beam having a wavelengthin the EUV range of 10 nm to 100 nm.

As described in the foregoing embodiments, the surface of a reticle istreated by decomposing the particles and a hydrocarbon layer depositedon a surface of the reticle and curing deposited oxide and the modifiedcomposition of the top layers of the reticle by UV radiation and ozonefluid. The treatment is performed with no solvent and by using the UVradiation and ozone fluid. As discussed, the treatment reduces theexposure time of the lithography operation and reduces lithographycosts.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

1. A method comprising: retrieving a reticle from a reticle library;transferring the reticle to a treatment device; releasing ozone fluidover a surface of the reticle; while the ozone fluid is over the surfaceof the reticle, irradiating the surface of the reticle with an incidentultraviolet (UV) radiation for a predetermined irradiation time to treatthe surface of the reticle; after the treatment, transferring thereticle to an exposure device for lithography operation to generate aphoto resist pattern on a wafer; imaging a surface of the wafer togenerate an image of the photo resist pattern on the wafer; analyzingthe generated image of the photo resist pattern to determine criticaldimension uniformity (CDU) of the photo resist pattern; and increasingthe predetermined irradiation time if the determined CDU does notsatisfy a threshold CDU.
 2. The method of claim 1, wherein: the ozonefluid is either an ozone water or an ozone gas, and the method furthercomprises: maintaining the treatment device, the exposure device, andthe reticle library under vacuum environment.
 3. The method of claim 1,wherein: the reticle is retrieved from the reticle library and istransferred to the treatment device by a robot arm of a wafer exchangesystem, and the method further comprises transferring the reticle fromthe treatment device to the exposure device by the robot arm.
 4. Themethod of claim 1, further comprising: projecting, by an incidentextreme UV (EUV) radiation, a layout pattern of the reticle onto a photoresist layer of the wafer; and developing the photo resist layer togenerate the photo resist pattern on the wafer.
 5. The method of claim4, wherein the incident UV radiation is generated from a UV source ofthe treatment device and the incident EUV radiation is generated from anEUV source of the exposure device.
 6. The method of claim 4, wherein thethreshold CDU is between one to two percent in 3 nm process for 3 nmsemiconductor node.
 7. The method of claim 6, further comprising:repeating the treatment, the projecting, the developing, the imaging,the analyzing, and the increasing a irradiation time, until thedetermined CDU satisfies the threshold CDU; and adjusting thepredetermined irradiation time to the irradiation time that correspondsto the threshold CDU.
 8. A method comprising: performing a treatment ofa surface of a reflective reticle in a treatment device, wherein thetreatment comprises: releasing ozone fluid over the surface of thereticle; and while the ozone fluid is over the surface of the reticle,irradiating the surface of the reticle by an incident ultraviolet (UV)beam of a UV source for an irradiation time to treat the surface of thereticle, wherein the treatment further comprises: focusing a reflectedUV beam from the surface of the reticle onto a detector to generate adetected signal; monitoring the detected signal during the irradiationtime; and stopping the treatment of the surface of the reticle andending the irradiation time when a percentage increase of the detectedsignal is below a threshold value in a specific amount of time; afterthe treatment, transferring the reticle from the treatment device to anexposure device for lithography operation; and projecting a layoutpattern of the reticle in the exposure device, using an incident extremeUV (EUV) radiation of an EUV source, onto a photo resist layer of awafer.
 9. The method of claim 8, further comprising: after theprojecting, developing the photo resist layer to generate a photo resistpattern on the wafer.
 10. The method of claim 8, wherein the treatmentfurther comprises; irradiating a first region of two or more at leastpartially non-overlapping regions on the surface of the reticle by theincident UV beam to treat the first region on the surface of thereticle; focusing a reflected UV beam from the first region of thesurface of the reticle onto the detector to generate the detectedsignal; monitoring the detected signal during the irradiation time; andstopping the treatment of the first region when the percentage increaseof the detected signal is below the threshold value in the specificamount of time.
 11. The method of claim 10, wherein the two or more atleast partially non-overlapping regions cover an entire surface of thereticle, the treatment further comprises: performing the irradiating,the focusing, the monitoring, and the stopping on other regions of thetwo or more at least partially non-overlapping regions on the surface ofthe reticle to treat the entire surface of the reticle.
 12. The methodof claim 10, wherein the UV source of the treatment device produces UVbeam with a wavelength between 100 nm and 300 nm, and wherein the methodfurther comprises: stopping the treatment of the first region when thedetected signal increases less than one percent in 20 seconds.
 13. Themethod of claim 8, wherein the EUV source of the exposure deviceproduces EUV radiation at a wavelength of 13.5 nm and the UV sourceproduces UV beam with a wavelength between 120 nm and 250 nm.
 14. Themethod of claim 8, further comprising: maintaining the exposure deviceand the treatment device under a vacuum environment.
 15. A semiconductormanufacturing system, comprising: a main controller; an analyzer modulecoupled to the main controller; a wafer exchange system having anextendable robot arm; a treatment device comprising: a first reticlestage configured for mounting a reticle; an ultraviolet (UV) lightsource; and a light detector system comprising a light detector; anexposure device comprising: a second reticle stage configured formounting the reticle; an extreme ultraviolet (EUV) light source; a stagefor holding a wafer; and an optical system, wherein: the main controlleris configured to command the UV light source to turn on, to irradiate UVradiation from the UV light source, and to treat a surface of thereticle in the first reticle stage of the treatment device byirradiating the surface of the reticle by the UV radiation of the UVlight source, the main controller is configured to allow release ofozone fluid from an ozone supply line over the surface of the reticleduring the irradiation with the UV radiation, the main controller isconfigured to command the light detector system of the treatment deviceto focus a reflected UV radiation from the surface of the reticle ontothe light detector of the light detector system to generate a detectedsignal and to send the detected signal to the analyzer module, theanalyzer module is configured to monitor the detected signal during anirradiation time, and to send a command via the main controller to theUV light source to stop a treatment of the surface of the reticle when apercentage increase of the detected signal is below a threshold value ina specific amount of time, after the treatment, the main controller isconfigured to command the wafer exchange system to transfer the reticle,by the extendable robot arm, from the treatment device to the secondreticle stage of the exposure device for lithography operation, andafter the transferring, the main controller is configured to command theEUV light source to turn on, to irradiate EUV radiation from the EUVlight source, and to project a layout pattern of the reticle, throughthe optical system, onto a photo resist layer of the wafer.
 16. Thesystem of claim 15, further comprising: a development system configuredto develop the photo resist layer of the wafer after the projection ofthe layout pattern of the reticle and to generate a photo resist patternon the wafer.
 17. The system of claim 16, wherein the exposure devicefurther comprises: an imaging device mounted over the stage for holdinga wafer, wherein in response to a command from the main controller theimaging device is configured to capture an image of the developed photoresist pattern on the wafer and to transfer the captured image to theanalyzer module, wherein the analyzer module is configured to determinea critical dimension uniformity (CDU) of the photo resist pattern on thewafer.
 18. The system of claim 15, further comprising: a reticle libraryconfigured to hold a plurality of reticles; and a pressure controllercoupled to the main controller, where the pressure controller isconfigured to maintain a pressure of the exposure device, the treatmentdevice, and the reticle library under a vacuum environment.
 19. Thesystem of claim 15, further comprising: a reticle library, wherein priorto the irradiating the surface of the reticle by the UV radiation, themain controller is configured to send a command to the wafer exchangesystem to retrieve the reticle from the reticle library and to transferthe reticle to the treatment device.
 20. The system of claim 15, whereinthe EUV light source emits an EUV light having a wavelength of 13.5 nmand the UV light source emits a UV light having a wavelength between 120nm and 250 nm, and wherein the analyzer module is configured to send acommand via the main controller to the UV light source to turn off tostop the treatment of the surface of the reticle when the detectedsignal increases less than one percent in 20 seconds.